Endoscopic imaging techniques for detecting early colorectal cancer

The detection of early colorectal cancer has improved notably since the introduction of bowel cancer screening programmes. This has created new challenges from endoscopic, histological and therapeutic perspectives. Here, we outline the limitations of current clinical practice and ways of implementing optical diagnosis to overcome these limitations.

Virtual chromoendoscopy without magnification for predicting or ruling out deep submucosal invasion is useful in real clinical practice for most lesions. However, magnifying virtual chromoendoscopy is needed to make an accurate diagnosis in nonulcerated narrow-band imaging international colorectal endoscopic (NICE) type 3 lesions or NICE type 2 lesions with depressed areas or of nodular mixed type. Finally, dye-based magnifying chromoendoscopy is needed in Japanese NBI Expert Team 2B lesions assessed with magnifying virtual chromoendoscopy.

A four-step strategy is proposed, combining white-light assessment, virtual chromoendoscopy without magnification, virtual chromoendoscopy with magnification and dye-based chromoendoscopy with magnification.